Motor vehicles with an internal combustion and/or electric engine exhibit a motor vehicle interior for accommodating individuals. Front and rear seats are here situated in the motor vehicle interior accommodating the individuals. The front seats are generally designed as a driver and passenger seat, and the rear seats are often designed as a rear seat bench with several rear seats. The motor vehicle generally exhibits an airbag for each of the two individuals on the front seats. Further situated in the motor vehicle is a seat belt retractor for the driver's seat and passenger seat, i.e., two seat belt retractors each for the driver's and passenger seat as front seats.
A deceleration sensor, for example an electronic deceleration sensor or mechanical deceleration sensor with a pendant control unit, detects a deceleration or negative acceleration of the motor vehicle or seat belt retractor, and once a prescribed limit for the deceleration has been exceeded, an energy absorption device is activated with a torsion rod. With the energy absorption device activated, energy absorption restrains the seat belt from being pulled out, meaning that the torsion rod deforms or twists when a high enough tensile force acts on the seat belt, so that lower restraining forces are exerted on the individual in the front seat by the seat belt in the event of an accident.
The energy absorption device makes it possible to pull the seat belt out of the seat belt retractor with a large force after activating the energy absorption device, so that while the individual on the front seat might move toward a steering wheel or dashboard and even come into contact with the latter, the activated airbag prevents this from happening, so that even though the seat belt is pulled out of the seat belt retractor through energy absorption, there is no danger that the individual on the front seat will directly contact the steering wheel or dashboard, since the airbag prevents this contact.
The individuals on the rear seats are also secured by seat belts, and the motor vehicle exhibits seat belt retractors for individuals on the rear seats for this purpose. Such seat belt retractors for a seat belt for an individual on the rear seat do not exhibit any energy absorption devices, but rather only a locking mechanism for securing the seat belt without energy absorption, meaning that once the locking mechanism has been activated, the seat belt can no longer be pulled out of the seat belt retractor, even when greater forces are acting on the seat belt. This is necessary to prevent individuals on the rear seats from contacting the front seats during an accident. Because the locking mechanism restrains the seat belt without energy absorption, the seat belt exerts very high restraining forces on the individuals during an accident, so that there is here a danger that individuals on the rear seats will be injured due to the highly active restraining forces.
Known from DE 10 2010 048 583 A1 is a seat belt system. A short circuit part is provided that short circuits the power supply clamps of the motor that retracts the seat belt, and the short circuiting of the power supply clamps prevents the seat belt retracted by the motor from being pulled out. DE 60 2004 003 663 T2 shows a seat belt retractor encompassing a receiving part for retracting a seat belt, a motor for generating a drive torque, so as to rotate the receiving part, and a force transmission mechanism for transmitting the drive torque of the motor to the receiving part. The force transmission mechanism is provided with a hypocycloid wheel mechanism that reduces the motor speed while transmitting the rotation of the motor to the receiving part.
Therefore, at least one object is to provide a seat belt retractor, a method for operating a seat belt retractor, and a motor vehicle in which individuals on the rear seats of the motor vehicle essentially make no contact with the front seats during an accident, despite which comparatively low restraining forces are exerted by the seat belt on the individuals on the rear seats during the accident. In addition, other objects, desirable features and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background.